Cooling of gas turbine engine flame tubes



D. E. MQRRISON COOLING OF' GAS TURBINE ENGINE FLAME TUBES Filed Dec. 23, 1950 Sept. 30, 1952 2 SHEETS-@SHEET 1 Sept. 30, 1952 D. E. MORRISON 2,612,023

- COOLING OF GAS TURBINE ENGINE FLAME TUBES Filed Dec. 23, 1950 2 SHEETS--SHEET 2 Sic' /NvENTo/ D. SHORE/50N PER Patented Sept. 3Q, 1952 Donaldv Ewan Morrison, Nobel, Ontario, Canada,

assignor to A. V. Roe Canada Limited, Peel, Onfi tario, Canada, a corporation s Application December 23,1950. serial Nc. 202,446

1o claims. (ci. fic-39.65)

This invention relates to combustion `systems for aircraft gas turbine engines and more particularly tc a llame tube constructionI which is cooled by a film of air. i"

Combustion of the fuel and air mixture in a gas turbine engine takes place within flame tubes provided for the purpose, and since considerable heat is generated in the process, the flame tube is frequently overheated. Moreover, inthe type of combustion chamber embodying a system for lpre-vapourizing the fuel and linjecting it` upstream into the flame tube,` there is the additional problem of excessive deposition ofrcarbon on the ame tube walls.

-to these problems has been the introduction of A suggested solution a ilm of cooling air in the flame tube, which flows along its internal wall, to insulate it from the adjacent combustion flame; however the proposals heretofore advanced for providing such a film of cooling air have invariably resulted in an undesirable increase' in weight of the combustion chamber assembly and have produced a lm interrupted by the-wakes of the variousspacing I means employed in the annular openings through which the air has been admitted.

Accordingly, it is the main object of'V this invention to provide means for directing an unbroken film of cooling air on the internal-walls of a flame tube; without materially increasing the weight of the combustion chamber assembly.

The above object and other objectsA and advantages of the invention will'be apparent from a study of thefollowing description, takenin conjunction with the accompanying drawings, in which like referencefcharacters indicate corre- I 4 surrounded in spaced relationship by afcoaxial g casing I5;' thus there fis `anannular space between the flame tube and the casing. i

'In the embodiment of the invention illustrated in Figs. 2 and 3, the flame tube .I4 is providedby a plurality of hollow coaxial' membersdisposed in longitudinal serial relationship; 'iThesei-in'clude the members' I6,` vI1, I8. and -I9 which"y aresos arranged that the upstreania'nd downstream' terminal portions of adjacent members are'in-spaced overlapping relationship. Considering; as'an example, the upstreamV or inner member`-16r-fand the adjacently downstream or outer' member-I1, it will be noted that the upstream terminalpo'rftiovn I 'Ia of outer member ITis in spaced overlapping relationship with respect to the downstream 'terminal portion'lb of inner 'memberA I B; 'and thus an annular gap 20 is provided therebetween.

l The upstream end I1c of the outenmemberfland the upstream end AIIc of the inner memberbear against each other'to 'provide 'a .closure for the upstream end of the gap 20. *A pluralityv offhcles 2l are formed in theupstream'terminal portion IIa of the outer member I1'opposite thefdownsponding parts throughout the several views, and

' in which:

Figure 1 is a broken-away side elevation of a typical gas turbine engine in which is incorporated a combustion system constructed in accordance with theinvention;

Figure 2 is a sectional side elevation of one of the combustion chambers shown inFiguref'l;

Figure 3 is a broken-away perspectiverof the flame tube provided in the combustion chamber;

and Y I v v Figures`4 and 5 Iare respectively a fragmentary sectional side elevation and a fragmentary' end elevation of an alternative flame tube construction made in accordance with the invention.

Referring to the drawings, a gas turbine engine comprises a compressorl, a turbine vI I for driv- -ing the compressor,l combustion chambers I2 disposed in series therebetween, anda tail cone I3. AEachcornbustionv chamber includes a flame tube stream terminal portion I6b of the-inner member to provide admission inlets for'air lromethe space between the casing and th ifflame'tube, the said air flowing into the llame tubevthrough'frthe vgap 20.

A tube 'plate' 22`iscircumferentiallyiengaged in a recess providedln :the upstreamfterminal portion Ilia of; the inner member1I6,;theitube plate, the'inner member and the'outer member I'I being securedrtogetherv by screws 23, Supported at one end by the tube'plate arefsymmetrlcally arranged vapourizer tubes 24 of any-suitable type, whichextend into the interior ofthe flametube. Centrally mounted in the tube .plate is a burner 25 supplied withfuelv from an external source (not shown) 'by a pipe.v 26.. `'Ihe burner is provided with a series'of jets 24a toveject'fuel into the registering vapourizer tubes 24. y

Whenv the engine is in operation, airis drawn into the compressor Il) whereits v pressure is raised, and it is thenv passed to the combustion chambers`l2 where `it is mixed `with fuel -and the mixture is'burned; the products of combustion expand and are finally exhausted `from-,the

tail cone I3 in a propulsive jet, afraction of their energy being expended in driving the *turbine* II` I which in turn drives the compressor IIL@` A portion ofthe compressed air entering: each combustion' chamber I2, enters the llame.. tube I4 through the vapourizer tubes 24,anothfer ,portion enters theflame tulleA throughthe members disposed in'lngitudir'ial serial'relation- :sh-ip; the downstream terminar perdoniof the 1" 'meer f se J presagi e terminar. por- ,Qli mmh@ i upstream end ofthe vgapma pluralityf ofwlioles being'v formed in? the upstream terminal portion i' of the outer memberoripcisite the downstream terminal portionr of vtheinner-member to provide .f-.admissioniinletsfor airgfrom-,the space between the casing and the flame tubef'into theflame tube through the gap.

5. In a combustion v'chsanflber'for a gas turbine eng-ine, through which a stream of airl is -con- ?"stfrainedto flow, a flame tube, l i! ing the `flame vtube in -spacedjirelationship-thereto 'and providing a space between the ii'anie'tube basing surroundand the casing, the said ame tube having a wall including inner and outer hollow coaxial members disposed in longitudinal serial relationship, the downstream terminal portion of the inner member and the upstream terminal portion of the outer member being in spaced overlapping relationship to provide an annular gap therebetween, a plate disposed transversely of the longitudinal axis of the flame tube, the said plate being in engagement with and supported by the upstream end of the upstream terminal portion of the outer member and also being in engagement with the upstream terminal portion of the inner member to close the upstream end of the gap, fuel supplying means supported by the plate and discharging into the flame tube, a plurality of holes being formed in the upstream terminal portion of the outer member opposite the downstream terminal portion of the inner member to provide admission inlets for air from the space between the casing and the flame tube into the ame tube through the gap.

6. In a combustion chamber for a gas turbine engine, through which a stream of air is constrained to flow, a fiame tube, a casing surrounding the flame tube in spaced relationship thereto and providing a space between the iiame tube and the casing, the said flame tube having a wall including inner and outer hollow coaxial members disposed in longitudinal serial relationship, the downstream terminal portion of the inner mem- .ber and the upstream terminal portion of the outer member being in spaced overlapping relationship to provide an annular gap therebetween,

' the upstream end'of the inner member bearing against the upstream end of the outer member to provide a closure for the upstream end'of the gap, a plurality of holes being formed in the up- --stream terminal portion of the outer member opposite the downstream terminal portion of the inner member to provide admission inlets for air from the space between the casing and the flame tube into the flame tube through the gap, a plate disposed within and supported by the upstream terminal portion of one of said members, and fuel supplyingmeans supported by the plate and discharging into the flame tube.

vl7. In a combustion chamber for a gas turbine engine, through which a stream of air is constrained to ow, a flame tube, a casing surroundouter member being in spacedverlappingf-relationship "toprovide v"ani-r annular g'api* bounded by the outer side of theinner membe anditlie'inn'er i side. of .the outer member, they otr 'side-'ot the upstreamterminal portion'ofthe inner member at' fits-upstream 'end bearing against-the inner iside-oftheupstream terminal-.portion-of the outer A -membe1- at :its'upstr'eamp-end-to provide 'ai clsure for :the upstream end;v `Vof i the gap', la' pluralitybf 'Y holes being formed in the upstream' terminal portion. of' the' outersmemb'er opposite'fthef-'downstream terminal portion of.theinner m'emberto .20.,

between the casin'g'an'd the-flame tube/into the flame ltube throughthe'gap", ai plate circumferentially supported'. by Athe' inner:` side of Lthe" upprovideV 'admissionf inlets for 1 air' from the* space stream terminal portion `of one of isaid `z'nexrlbers, and fuel supplying means 3supported=-bythe plate and discharging into the flame tube.

8. In a, combustion chamber for a gas turbine engine, through which a stream of air is constrained to flow, a flame tube, a casing surrounding the flame tube in spaced relationship thereto and providing a space between the flame tube and the casing, the said llame tube having a wall including inner and outer hollow coaxial members disposed in longitudinal serial relationship, the downstream terminal portion of the inner member and the upstream terminal portion of the outer member being in spaced overlapping relationship to provide an annular gap bounded by the outer side of the inner member and the inner side of the outer member, the outer side of the upstream terminal portion of the inner member at itsl upstream end bearing against the inner side of the upstream terminal portion of the outer member at its upstream end to provide a closure for the upstream end of the gap, a plurality'of holes being formed in the upstream terminal portion of the outer member opposite the downstream terminal portion of the inner member to provide admission inlets for air from the space between the casing and the ame tube into the flame tube through the gap, a plate circumferentially supported by the inner side of the upstream terminal portion of the inner member, and

fuel supplying means supported by the plate and discharging into the flame tube.

9. In a combustion chamber for a gas turbine engine, through which a stream of air is constrained to ilow, va ame tube, a casing surrounding the flame tube in spaced relationship thereto and providing a space between the flame tube and the casing, the said flame tube having a wall including inner and outer hollow coaxial members disposed in longitudinal serial'relationship, 4the downstream terminal portion of the inner member and the upstream terminal portion of the outer member being in spaced overlapping relationship to provide an annular gap bounded in part by the outer side of the inner member and the inner side of the outer member, a plurality of holes being formed in the upstream terminal portion of the outer member opposite the downstream terminal portion of the inner member to provide admission inlets for air from the space between the casing vand the flame tube into the flame tube. through `the @emmene penuria latefcircumterentiaily *supporteda -by the -jfinner'fside of the upstreamfterminl portion--. of *the outer ;.membe1t,. the inner vrmember rbeing. :sefcured Atofanriz-fSuilpori:ed .by the. plate. "the periphyferalfportionnf :the plate providing a. `closure yfor v-the :upstream 'iend of the gap,- and fuelfsupplfz- -eingfmeansfsuppoztedby the-plate and discharg- .-ngxintortheflaxne-tube y' 1D.; Ima.l combustion chamber fior 'a ges turbine -fengine-g-through whichwa Vstreem of air isA confstrrainedr'toxiiewga flame tube. a casing'surroundthe flame tubein.- spaced relationship thereto @anni providing. a. space between the ametube fraud. the casing', :the-'said Viarne tube;ha.ving:a=wa11 ncludngfnner and outer hollow coaxiaimembers; `dismosed gin: ...longitudinal serial.'` relationship, downstreamptermnal Aportion ,of :the :inner memberjandvtheupstreamterminal portion of the wouter/:member beingin :spaced .'mzerlanppingsre- Jiationship,to-providean annular gap bounded by thergouterl-side of. theeinner: member and the inner sidewgof .the outer: memben, the; outer side of the upstream terminal portionxof .the inner member fat fits' ,upstream end bearing against the Vinner iside of thef upstream terminal portion-of "the "outvvereinenzibel.- 'at-itev upstreamfend totprovixiefafclosure-zforftheiupstreamrendfofhthefgamra, plurality of 'holes: lbeine.'*formed in f. the upstream` termina] portion ofthe outer member-opposite the-:downtstream .terminal .portion 'of the-inner :member to .provide- `admission inlets :for veir VVfrom the :space between thecasing-,and the flame tube into the ame tube throughi thez gapfanfannuiar irecess in thel inner side of lthe upstream,- terxninaL portion of. `the innervfmember, .aplate circumferentially `engagedin therecess for support vbythe .inner member, and :.fuelfsupplying meane'sup- .ported .by .the Ap1atef.and-.vdischargingt into :the

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